This invention relates to a front-loading medical injector and a syringe for use therewith, and more particularly to a front-loading medical injector apparatus wherein a syringe of special construction is mountable upon and removable from a front wall of an injector housing by a first readily releasable mechanism, while a plunger in the syringe is simultaneously connected to or dissembled from an injector drive member by a second readily releasable mechanism. U.S. Pat. No. 4,006,736, issued to R. J. Kranys et al. on Feb. 8, 1977, and entitled, xe2x80x9cAngiographic Injectorxe2x80x9d, which is assigned to the same Assignee as the subject application, discloses an angiographic injector apparatus for injecting contrast media into the vascular system of an animal, in which angiographic syringes are rear-loaded into a pressure jacket of the injector. More specifically, the apparatus comprises a rotatable turret which carries a pair of the pressure jackets and which is rotatable so that when one of the pressure jackets, into which an angiographic syringe has been rear-loaded, is in an injection position, the other pressure jacket is in a position in which an associated angiographic syringe can be rear-loaded. Subsequently, when injection of contrast media from the first syringe is completed, the turret is rotated to move the first syringe to an unloading-loading position, with the second pressure jacket and the angiographic syringe then being moved into the injection position. In this apparatus, when each of the pressure jackets and its associated syringe has been located in the injection position, a drive member of the injector is moved forward to become drivingly engaged with a plunger in the syringe; however, the manner of engagement between the drive member and plunger is such that the drive member cannot be retracted without also retracting the plunger, which can cause body fluids of the animal to be retracted into the syringe unless the syringe is first disconnected from the animal.
An improved apparatus over the apparatus as disclosed in the Kranys et al. patent, is disclosed in U.S. Pat. No. 4,677,980, issued to D. M. Reilly et al. on Jul. 7, 1987, and entitled xe2x80x9cAngiographic Injector and Angiographic Syringe for Use Therewithxe2x80x9d, which also is assigned to the same Assignee as the subject application, In this apparatus, a drive member of the angiographic injector can be drivingly connected to, or disconnected from, a plunger of an angiographic syringe at any point along the path of travel of the plunger by a readily releasable mechanism. Thus, the apparatus of the Reilly et al. patent represented certain improvements over the Kranys et al. patent. However, the apparatus of the Reilly et al. patent, like that of the Kranys et al. patent, is of a rear-loading type comprising a pair of pressure jackets mounted upon a rotatable turret for moving the pressure jackets and syringes therein between injection and loading positions.
Accordingly, a need exists for a front-loading medical injector and a syringe of special construction so that the syringe can be readily and securely front-loaded directly and accurately in a desired position on the injector, thereby facilitating the loading-unloading operation, and a primary purpose of this invention is to provide such an arrangement with its various attendant advantages. Further, in certain instances, it is desirable that the syringe not be enclosed in a pressure jacket, in order that an operator be able to view the status of the syringe visually during an injection operation. By allowing the operator to see the syringe, the operator can, e.g., determine whether the syringe is empty or full, determine if it is being filled too fast and/or introducing too many air bubbles, when the syringe is filled, and the amount of contrast that has been delivered or remains in the syringe during a procedure. Another purpose of this invention is, in one embodiment, to provide an injector apparatus of such construction.
In general, in accordance with the invention, a readily releasable mechanism is provided for supporting a syringe on a front wall or an injector housing for an injection operation. For this purpose, the readily releasable mechanism includes at least one retaining portion on the mounting mechanism releasably engageable with a mating retaining portion on the syringe. Further, an actuating mechanism of the injector includes a drive member, which is connectable to a plunger in the syringe for controlling the movement of the plunger in the syringe.
More specifically, the readily releasable mechanism is an interlocking mechanism which is activated and released upon rotation of a rearward portion of the syringe relative to the front wall of the injector housing. At the same time, a second readily releasable interlocking mechanism for connecting the injector drive member to the syringe plunger, and which also is activated and released upon rotation of the syringe relative to the front wall of the housing, interconnects the drive member and the plunger. The first readily releasable mechanism may comprise a mounting mechanism on the front wall of the housing having at least a pair of slots for receiving retaining flanges on the rearward end of the syringe there through, with the syringe then being rotated to engage the flanges behind associated retaining flanges of the mounting mechanism. The second readily releasable mechanism comprises respective radially projecting parts on the drive member and the plunger, which become drivingly engaged in a similar manner upon rotation of the syringe and the plunger.
The first readily releasable mechanism may be further defined by the mounting mechanism on the injector housing front wall having an annular sealing member against which a resilient annular sealing member on the syringe becomes seated as the syringe is positioned on the mounting mechanism, with the resilient annular sealing member and the retaining flanges on the syringe receiving the retaining flanges on the mounting mechanism there between with an interference fit. An audible-and-tactile indicator mechanism, alignment arrows, and/or alignment dots also may be provided to detect when the syringe has been essentially rotated into its desired mounted position against suitable stops, with this mechanism then further functioning to discourage reverse rotation of the syringe on the injector housing. An indicator mechanism for providing liquid media injection information to an injector controller, and a sensor for reading the indicating mechanism, also may be provided on the syringe and the injector housing, respectively. The syringe also may include a mechanism which provides a visual indication of whether the syringe still includes injection liquid, may have an injector nozzle of reduced diameter surrounded by a screw-threaded cylindrical attachment portion at its injection end (the reduced diameter nozzle serving to minimize the amount of contrast that remains in the syringe after the plunger has been fully extended), may be provided with reinforcing ribs which are longitudinally spaced so as to also function as volumetric gradations, and/or may be formed of relatively strong clear plastic.
In another embodiment of the invention, which utilizes a pressure jacket, the pressure jacket is in the form of an elongated tube having one end mounted on the front wall of the injector housing, and having an opposite open outer end. In a syringe mounting operation, a syringe is inserted into the open end of the tubular jacket until an inner end of the syringe engages against a seat mechanism on the injector housing front wall. During this insertion operation, retaining flanges adjacent the forward end of the syringe pass through slots in the open end of the tubular pressure jacket, whereupon the syringe is rotated to engage the flanges behind corresponding mating retaining flanges at the open end of the jacket. As the syringe is rotated, a plunger in the syringe also rotates into driving engagement with a drive member of the injector. An outer injection end of the syringe also may be provided with reinforcing-handle members.